Antenna feed horn



March 26, 1957 c. w. DAVIS ANTENNA FEED HORN Filed April 21, 1953 INVENTOR. cm RLES w. DAVIS A lfarn g/ 44 FIG. 4

FIG. 3

United States, Patent ANTENNA FEED HORN Charles W. Davis, Boston, Mass., assignor, by mesne asslgnments, to the United States of America as represented by the Secretary of the Navy Application April 21, 1953, Serial No. 349,997

4 Claims. (Cl. 343-775) The present invention concerns an antenna and in particular concerns an antenna feed horn and matching arrangement therefor. g

In many microwave installations, it is necessary to have a relatively long waveguide feeding the antenna. Such waveguides may be matched at the entrance to the reflector but when so matched there is still a length of waveguide extending through the dish with a reverse turn for feeding the horn which faces the concavity of the dish. The invention improves upon the prior art devices by providing for the waveguide an adjustable connection through the reflector dish, and by further providing means for adjusting the feedline match with respect to the input in the horn. An adjustment rod is extended through the antenna dish to the horn for this purpose.

An object of the invention is to provide an antenna.

Another object is to provide an antenna feed horn and matching arrangement therefor.

Another object is to provide in connection with a microwave antenna an adjustable connection through the reflector dish and means for adjusting the feed line match with respect to the input in the horn.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a side elevation of a preferred embodiment of the invention,

Fig. 2 is a fragmentary view seen from the right of Fig. 1,

Fig. 3 is a fragmentary detail taken along line 33 of Fig. 2, and

Fig. 4 is a fragmentary detail taken along line 44 of Fig. 2.

In Fig. 1 there is shown a dished reflector 11 of parabolic shape in axial section and having an outwardly turned rim 12, the shape of the rim being more clearly shown in Fig. 3. A frame 13 is provided for supporting the parabolic dished reflector 11. The frame 13 comprises in part a pair of tubular rings 15 and 16. The tubular ring 15 is secured to the outer side of the reflector 11 adjacent its rim 12 by means of a series of bolts and nuts 17; the instant embodiment of the invention includes twenty-six of these bolts and nuts.

The tubular ring 16 is secured to the reflector 11 by means of four channeled support straps 19. Each of the straps 19 is welded at one of its ends to the tubular ring 16 at a portion thereof remote from the reflector 11 and the other end of each of the straps 19 is riveted at two places to the reflector 11. The two tubular rings 15 and 16 are not only separately secured to the reflector but are also joined to one another by means of strut-like members 21 and 22 welded to or otherwise aflixed to rings 15 and 16. The assembly of tubular rings 15, 16 and strutlike members 21 and 22 provides the rigid frame 13.

A mounting ring 24 is coaxially secured to the outer 2,786,998 Patented Mar. 26, 1957 "ice side of reflector 11 by means of a plurality of aluminum rivets 26. The mounting ring 24 (Fig. 4) is provided with tapped holes 27 at four equally spaced arcuate intervals. A circular section of the reflector portion included by the mounting ring is cut away at 25.

A clamp support 29 whose perimeter is substantially a square is provided with an opening 28 in each of its four corners, each of which openings is adapted to align with one of the tapped holes 27 in mounting ring 24. Bolts 31 and washers 32 secure the clamp support 29 to the ring assembly 24. Collars 34 are provided to space the clamp support 29 from the ring assembly 24; collars 34 may be welded to the mounting ring 24 at each of said tapped hole positions. The clamp support 29 is provided with an axial opening 36 which is frustro-conical in shape. The rim 38 of the clamp support opening 36 has a plurality of tapped holes 37. A plurality of bolts 39 having washers 41 are adapted to be threaded into openings 37.

A clamp 44 having a frustro-conical portion 45 is adapted to be mounted in mating relation in the axial opening of the clamp support 29. The clamp is provided with a reduced axial shank portion 47 extending beyond the larger end of its frustro-conical portion and is hollow as at 49. Each of its ends have a rectangular opening 51 for receiving a waveguide connection 55. The clamp 44 may be provided with suitable longitudinal slots (not shown) to allow for radial compression and expansion. The larger end of the frustro-conical portion 45 has a stepped edge 52. A ring 53 having a plurality of openings corresponding to the openings 37 in the clamp support 29 is adapted to be fitted over clamp 44 and retained in place by means of screws 39 and washers 41.

In operation the waveguide connection 55 to the feed horn 56 can be adjusted axially and radially of the parabolic reflector dish 11 from the back. To perform the adjustment operation the bolts 39 for retaining ring 51 are loosened permitting the clamp 44 to move axially. As a result of the axial movement, radial clamping pressure on the Waveguide 55 is released permitting the waveguide to be adjusted. By means of the adjustment the antenna may be accurately focused.

Adjustment of the feed line match with respect to the input in the horn is accomplished by actuating an adjustment rod (not shown) extending through the antenna dish 11 to the horn 56.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A microwave antenna comprising a dished reflector, said reflector being formed with an opening axially thereof, a rigid supporting framework for said reflector, a mounting ring secured to the outer surface of said reflector coaxially thereof, a clamp support secured to said mounting ring axially of said reflector and seating in the opening in said reflector, said clamp support constructed and arranged so as to provide a continuation of the inside surface of said reflector, said clamp support further formed with a frustro conical opening coaxial with said reflector, a frustro conical hollow clamp formed with a reduced axial shank portion and further formed with at least one longitudinal slot to allow for radial compression, a waveguide axially supported in said clamp, a bolt engaged clamping ring, said clamping ring engaging said clamp to cause said clamp to move axially in the frustro conical opening of said clamp support for selectively gripping or releasing said waveguide.

2. A microwave antenna comprising a dished reflector,

r '2,'786,998 V V said reflector being formed with an opening axially thereof, a mounting ring secured to the outer surface of said reflector coaxially thereof, a clampsupport secured to said mounting ring axially of said reflector and seating in'the opening in said reflector, saidclarnp support constructed and arranged so as to provide a continuation of the inside surface of said reflector, said clamp support further formed with a frustro conical opening coaxial with said reflector, a frustro conical hollow clamp formed with a reduced axial shank portion and further formed with at least one longitudinal slot to allow for radial compression, a waveguide axially supported in said clamp, a bolt-engaged clamping ring, said clamping ring engaging said clamp to cause said clamp to move axially in the frustro conical opening of said clamp support for selectively gripping or releasing said waveguide.

3. A microwave antenna comprising a-reflector, said reflector being formed with an opening axially thereof, a clamp support secured to convex side of said reflector axially thereof and seating in the opening in said reflector, said clamp support constructed and arranged as to provide a continuation of the inside surface of said reflector, said clamp support further formed with a frustro conical opening, coaxial with said reflector, a frustro conical hollow clamp formed with a reduced axial shank portion and further formed with at least one longitudinal slot to allow for radial compression, a waveguide axially supported in said clamp, and a clamping ring bolted to said clamp support for engaging said clamp to cause said clamp to move axially in the frustro conical opening of said clamp support for selectively gripping or releasing said waveguide.

4. A microwave antenna comprising a reflector, said reflector being formed with an opening axially thereof, a clamp support secured tothe convex side of said reflector axially thereof, and seating in the opening in said reflector, said clamp support constructed and arranged so as to provide a continuation ofthe inside surface of said reflector, said clamp support further formed with a frustro conical opening coaxial with said reflector, a frustro conical hollow clamp formed with at least one longitudinal slot to allow for radial compression, a waveguide axially supported, in said clan-1p, and a clamping ring bolted to said clamp support for engaging said clamp to cause said clamp to move axially in the frustro conical opening of said clamp support for selectively gripping or releasing said waveguide.

References Cited in the file of this patent UNITED STATES PATENTS 

